An IP-storage area network (IP-SAN) in which an internet small computer system interface (iSCSI), a fibre channel (FC), or an internet protocol (IP) is employed as a communication protocol has been widely used (for example, refer to Japanese Laid-open Patent Publication No. 2006-331392 and Japanese Laid-open Patent Publication No. 2006-331458). When the IP-SAN is used between a server device and a storage device, a block flows at high speed between the devices. Here, a block is one aggregation obtained by storing a plurality of pieces of data. Thus, communication of a plurality of pieces of data in a block unit is called block access, for example.
In the block access described above, a file system is used. The file system is one of functions which are incorporated in an operating system (OS) and is implemented on a server device. When the file system receives a request of processing, such as reference and updating of data, from a terminal device which is connected to the server device, the file system calls a block in which the data is stored from the storage device and returns the block, in a form of block, to the storage device when processing on the data is completed.